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1 Suggested levels for Guided Reading, DRA, Lexile, and Reading Recovery are provided in the Pearson Scott Foresman Leveling Guide. Life Science Ecosystems of the Rain Forests Genre Expository nonfiction Comprehension Skills and Strategy Fact and Opinion Main Idea and Details Graphic Organizers Text Features Captions Diagram Map Glossary Scott Foresman Reading Street ì<(sk$m)=bdgabi< +^-Ä-U-Ä-U ISBN by M. J. Spackman

2 Vocabulary basin charities equator erosion Ecosystems of the Rain Forests evaporates exported industrial recycle tropics Word count: 1,790 by M. J. Spackman Note: The total word count includes words in the running text and headings only. Numerals and words in chapter titles, captions, labels, diagrams, charts, graphs, sidebars, and extra features are not included. Editorial Offices: Glenview, Illinois Parsippany, New Jersey New York, New York Sales Offices: Needham, Massachusetts Duluth, Georgia Glenview, Illinois Coppell, Texas Ontario, California Mesa, Arizona

3 What Is a Rain Forest? A rain forest is a wet, wooded place. In some rain forests, as many as 400 inches of rain may fall in a year. Rain forests have four layers. The lowest level is the forest floor. The middle layers are the understory, which is shaded by tall trees, and the canopy, which is like a roof. The top layer is called the emergent layer. This is where the tops of some trees rise above the canopy. Rain forests are large ecosystems. Each life form depends on the other life forms that live there. Tropical rain forest Every effort has been made to secure permission and provide appropriate credit for photographic material. The publisher deeply regrets any omission and pledges to correct errors called to its attention in subsequent editions. Unless otherwise acknowledged, all photographs are the property of Scott Foresman, a division of Pearson Education. Photo locators denoted as follows: Top (T), Center (C), Bottom (B), Left (L), Right (R), Background (Bkgd) Opener Wolfgang Kaehler/CORBIS; 1 Gallo Images/CORBIS; 3 Jim Zuckerman/ CORBIS; 4 Ralph A. Clevenger/CORBIS; 5 Michael & Patricia Fogden/CORBIS; 6 Gary Braasch/CORBIS; 8 Gary Braasch/CORBIS; 9 Gary Braasch/CORBIS; 10 Alastair Shay; Papilio/CORBIS; 11 Jay Dickman/CORBIS; 12 Craig Tuttle/CORBIS; 13 Michael & Patricia Fogden/CORBIS; 14 Gallo Images/CORBIS; 15 Tom Brakefield/CORBIS; 16 Michael & Patricia Fogden/CORBIS; 19 David Muench/CORBIS; 20 Galen Rowell/ CORBIS; 21 Wolfgang Kaehler/CORBIS; 23 Wolfgang Kaehler/CORBIS ISBN: Copyright Pearson Education, Inc. All Rights Reserved. Printed in China. This publication is protected by Copyright, and permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form by any means, electronic, mechanical, photocopying, recording, or likewise. For information regarding permission(s), write to: Permissions Department, Scott Foresman, 1900 East Lake Avenue, Glenview, Illinois V0H

4 What Is an Ecosystem? An ecosystem is made up of plants, animals, and nonliving things that occupy an area. If one part of the system is changed, the entire system may be affected. Every natural environment even your own flower garden is an ecosystem that has a cycle of life and death. In your flower garden, the flowers depend on earthworms that recycle nutrients in the soil. The bees that visit the flowers help to produce a new generation of plants. The life cycle continues as long as the ecosystem is not disturbed. Rain also helps your flowers grow. The moisture that is not used by the flowers evaporates when the sun comes out. It is then recycled when it becomes rain. Within each ecosystem there are producers and consumers. In a rain forest, the plants are producers. They make food. Animals and humans are consumers. They eat food. Organisms that cause decay, such as fungi and bacteria, help break down food. They also create nutrients for other living things. A great variety of animals and plants make their homes in rain forests. Unfortunately, rain forests are disappearing at an alarming rate. Understanding the ecosystems of rain forests can help us know how important it is to save them. Bees are needed for flowers to live. More than 2,000 kinds of butterflies call the Atlantic coast rain forests home. Many of these are in danger of extinction. 4 5

5 Two Types of Rain Forests There are two types of rain forests. Steamy rain forests are located in a region called the tropics. The tropics lie near the equator. The weather there is warm and wet all year long. There are now about two billion acres of tropical rain forest. Once there were many more. Rain forests also grow in a cooler, temperate climate. There are only about 75 million acres of temperate rain forests. Most of these stretch along the northwestern coast of the United States. But there are also temperate rain forests in New Zealand, Chile, and Australia. The ecosystems of both types of rain forests are threatened by human beings and our industrial world. Tropic of Cancer Equator Tropic of Capricorn The area of Earth that lies between the Tropic of Cancer and the Tropic of Capricorn contains the hot, wet regions known as tropical rain forests. 6 7

6 The Tropical Rain Forest Tropical rain forests are home to a huge variety of plants and animals. In one four-square-mile section of a rain forest in the Amazon River Basin of South America, scientists have identified 750 kinds of trees. The Forest Floor The floor of a tropical rain forest is mostly free of undergrowth. This is because very little sunlight can go through the thick upper canopy and understory. Without sunlight plants cannot live. The leaves, twigs, and dead insects on the forest floor break down quickly in the warm and wet conditions. Underneath the decaying leaves are fungi. The fungi feed off the decaying matter. This process enriches the soil and tree roots. The floor of the forest is also home to worms, insects, ground-feeding birds, and snakes. Each of these creatures has a role in the rain forest ecosystem. 8 9

7 One of the most interesting rain forest creatures is the leaf-cutter ant. Ants live in a colony, or group. Each ant has a job. Scout ants find trees. Large, strong-jawed ants follow a trail left by the scout ants. The large ants cut the leaves from the tree. Other ants carry the leaves back to the colony. They are helped by small ants that ride on top of the leaves to protect them from flies. In the colony, the ants chew the leaves into a pulp. That will feed the fungi that serve as the ants food. Once again, a cycle is formed. Rain forests of the Amazon Basin and Malaysia may be flooded many months of the year. Many of the trees are completely covered by water, yet they survive this flooding. The fish that swim in the flooded forest depend on the trees above for food. The trees produce fruit that drops into the water and is eaten by fish. The trees also depend on the fish. When the fish eat the fruit, they scatter the seeds. Then the seeds can grow into more trees. It might seem that the forest floor would be deep with rich soil that is good for farming, but this is not true. The soil is thin and nutrient-poor because too many plants grow in it. Leaf-cutter ants at work Leaf-cutter ants live in colonies. A young person canoeing in the Amazon Basin in Brazil 10 11

8 Here is another example of how living things depend on one another. There is a certain orchid in the rain forests of the Amazon Basin. This orchid depends on one kind of bee for pollination. If conditions in a forest change so that the bee cannot survive there, the orchid also disappears. The Brazil nut tree depends on this same orchid for pollination. A planter who grows Brazil nut trees must also grow the kind of orchid that the bees draw nectar from. Otherwise, the trees will not produce nuts. 12 The Understory Between the forest floor and the canopy is the understory. Plants that live in this layer are either shadelovers or young trees trying to reach sunlight above. When a large tree falls, it often pulls down other trees. The fallen trees create a light gap. Sunlight fills the gap. The young trees, climbing vines, and seeds on the forest floor use the light to grow. Among the greenery and branches of the understory, birds and insects fly. Plants that live on trees often produce blooms that appear to grow from the tree trunks. These flowers, including orchids, attract hummingbirds that feed on the nectar and assist in the plant s pollination. The hummingbird s long pointed beak allows it to easily drink the nectar of the rain forest s flowers. 13

9 Small mammals swing and scramble among the branches and vines of the understory. They climb easily with their handlike paws and quick feet. Among these is the lemur of Madagascar, an island nation off the east coast of Africa. Lemurs are endangered animals. Before human beings arrived in Madagascar, fourteen more species of lemur lived in the rain forests. The larger lemurs were hunted to extinction. Today, charities are collecting funds to protect the remaining lemurs and their habitat. A ring-tailed lemur leaps from tree to tree. 14 Another endangered rain forest mammal is the jaguar. The jaguar is at the top of the food chain in the rain forest. If it disappears, the populations of the animals it feeds on may increase too much. Then the balance of the ecosystem may be upset. 15

10 A sloth hangs high in a tree in the rain forest canopy The canopy trees support vines and even other trees. One is the strangler fig. The seed of this tree grows in branches of another tree. It then sends a root down the trunk of its host tree to the ground. There it begins to grow more roots, stems, and leaves. The strangler fig s roots cover the host tree, causing it to die. However, its fruit feeds monkeys and birds. So the strangler fig is an important part of the ecosystem. The sloth lives its entire life in the canopy. Sloths have adapted so well to life in the treetops that they almost never come to the ground. They can no longer walk upright when they do. Emergent Tree The Canopy The tops of the tall trees of the rain forest form its canopy. It is like an umbrella above the forest. The canopy is exposed to the sun, heat, wind, and rain. The emergent trees above the canopy are even more exposed. The emergent trees and the canopy trees capture the solar energy that fuels the entire rain forest ecosystem. Most of the organisms of the rain forest live in the trees of the canopy. Some trees provide woods used around the world. Mahogany, a reddish-brown wood used in furniture and boat frames, comes from tropical rain forests. It is becoming more rare and expensive. Teak, rosewood, and ebony are also exported by rain forest countries to sell around the world. The lumber industry provides employment and income for people. But it also endangers the ecosystem of the rain forest. 16 Canopy Understory 17

11 The Temperate Rain Forest The temperate rain forests are not as warm as the tropical rain forests. Usually, high temperatures in the summer are about 70 degrees Fahrenheit, and high temperatures in the winter stay around 40 degrees Fahrenheit. The temperate rain forest does not receive the same rain as the tropical rain forest. Still, there can be up to 167 inches of rain a year. The Canopy The living things in the temperate rain forest also depend on one another. The Douglas fir s needles are home to fungi, algae, and bacteria. The tiny bacteria draw their nutrition from the tree, and they also protect it. Other organisms on the tree might harm it if the bacteria were not there for them to eat. As in the tropical rain forest, some trees grow on other trees. The big-leaf maple tree sends tiny roots into other plants to draw nutrients from them

12 The Understory In the Olympic Rain Forest of the northwest United States, elk are important. They play a special part in the ecosystem of the understory. Scientists fenced off areas of the rain forest to see what happens when elk cannot go there. Several problems occurred. The open space of the understory became tangled with plants. The plants then had to fight for space. Some plants that died off were the elks most healthful food. The elk could not find the food they needed. In addition, there are bears that feed on the grass underneath those plants. They also lost their food source, because the grass became a tangle of vines and roots

13 The Forest Floor The trunks of fallen trees are an important part of the forest floor s ecosystem. At one time, people thought that the giant logs were just another kind of forest waste. But these dead tree trunks, called nurse logs, are important. They help prevent erosion, and they give shelter to snakes, chipmunks, and birds. The nurse logs also offer a rich bed for tree seedlings. When a tree falls and its enormous trunk becomes a nurse log, it decays to become a plant nursery. The cycle of life continues. Summary We have learned how the ecosystems in the rain forest work. We know that all living things in the rain forest depend upon one another. We also know that humans can affect the future of the rain forest. If we continue to change the rain forest, we may kill off many of its living things. We must protect the ecosystem of this special environment

14 Glossary Reader Response basin n. an area drained by a river or tributary. charities n. groups that help or assist. equator n. the imaginary circle around Earth s surface that divides Earth into the Northern and Southern Hemispheres. erosion n. an act or process of wearing away. evaporates v. converts or changes into vapor. exported v. transported or traded abroad. industrial adj. characterized by highly developed industries. recycle v. reuse or adapt to another use. tropics n. region of Earth s surface lying between the Tropic of Cancer and The Tropic of Capricorn (23 45 north to south latitudes). 1. Read the following sentence: The rain forests are home to a variety of animals and plants. Is this sentence a fact or an opinion? How can you tell? 2. Using the diagram on page 17 for reference, tell something you learned about each level of the rain forest. Make a graphic organizer to help you. 3. Copy this chart on a separate piece of paper. Look the words up in a dictionary and find forms of the words that have different endings. Copy those words and their meanings. Be prepared to use each word in a sentence. Word New word New meaning charity evaporate industry 4. What information does the caption on page 15 tell you that is not provided by the photograph? 24